High solids ethylene acrylic acid aqueous dispersions and methods of producing same

Abstract

A uniquely treated bead of ethylene acrylic acid (EAA) capable of forming a high solids aqueous dispersion in excess of 38% solids wherein the EAA may be prepared by either batch or continuous processes wherein the EAA is substantially fully reacted with ammonia, sodium or potassium in little or substantial absence of water, followed by a separate aqueous dispersion step, resulting in a unique and quick-drying dispersion material highly useful in coating, adhesive, laminating, ink and similar processes, and wherein operating expense and environmental concerns are at a minimum as a consequence thereof. The treated EAA may be prepared in a substantially dry to merely moist state for incorporation into an aqueous dispersion with high percentages of EAA having either higher or lower molecular weight with low viscosities as compared to heretofore.

What is claimed is: 
     
       1. A process for the production of a reacted ethylene acrylic acid (EAA) product comprising the steps of: providing a quantity of EAA polymer,   selecting a reactant from the group consisting of ammonia, ammonium hydroxide, sodium hydroxide, and potassium hydroxide,   adding a quantity of the selected reactant in the range of 0.10 to about 0.25 mole ratio to the EAA under dry conditions in an amount sufficient for the selected reactant to swell the EAA polymer to expose reactor sites of the molecule so that the positive ions of the selected reactant can reach the reactor sites of the EAA molecules thereby to form the corresponding EAA salts thereat,   mixing the selected reactant and the EAA, thereby permitting the same to react together to form EAA salts as a dry product with no additional water added thereto other than that initially present in the said selected reactant.   
     
     
       2. The process of claim 1 wherein the reaction takes place in a closed vessel. 
     
     
       3. The process of claim 1 further comprising the step of terminating the reaction upon development of a vacuum in the closed vessel. 
     
     
       4. The process of claim 1 wherein said adding the mixing steps occur at room temperature and without the positive addition of external heat. 
     
     
       5. The process of claim 1 wherein said adding and mixing steps are effected in an extruder, and further comprising the step of extruding the said dry product from the extruder. 
     
     
       6. The process of claim 5 further comprising the step of severing the extruded product into discrete pieces. 
     
     
       7. The process of claim 1 wherein said EAA polymer is in the form of discrete beads. 
     
     
       8. The process of claim 1 further comprising the step of admixing a solvating bead-swelling medium to the EAA at the said mixing step of the selected reactant and the EAA to facilitate ready reaction of the EAA with the selected reactant to form the EAA salts. 
     
     
       9. The process of claim 8 wherein the bead-swelling medium is selected from the group consisting of isopropyl alcohol (IPA), n-methyl pyrrilidone (NMP), and propylene glycol. 
     
     
       10. The process of claim 8 wherein said adding and mixing steps occur at room temperature and without the positive addition of external heat. 
     
     
       11. The process of claim 1 further comprising the step of subsequently admixing the reacted EAA with water to form an aqueous dispersion of the EAA in the water vehicle. 
     
     
       12. The process of claim 11 wherein the proportion of EAA solids in the dispersion is between 35% and 55%. 
     
     
       13. The process of claim 12 wherein the proportion of EAA solids in the dispersion is 38% or greater.